AS3691
Product Brief
austriamicrosystems
Product Brief
AS3691
4 Precision 400mA Current Sources for RGB and Single Color Leds
1 General Description
The AS3691 features four high precision current
sources for driving up to four LED strings (RGB or
single color leds). Each of the four currents sources
can be controlled independently by PWM inputs.
The full scale current value is set by external
resistors.
Very wide output voltage current source voltage
compliance
−
Down to 0.41V
2)
−
Up to 15V
Integrated overtemperature protection
Separate sense pads (Rfb1-Rfb4) for easy and
precise PCB Layout
Package
−
DIE
−
QFN24 4x4mm
15V is sufficient for most applications as the
AS3691 dose not switch off the LED current
completely
2)
2 Key Features
4 x 400mA constant current outputs
Programmable with external resistors
4 independent PWM inputs
Absolute current accuracy +/-0.5%
’
Automatic Supply Regulation’ to reduce power
1)
dissipation
1)
3 Applications
General Lighting
Backlighting
RGB Backlighting for LCD TV/Monitors with
White Color Balancing
Patent Pending
4 Application Diagrams
Figure
1 – Application Diagram of AS3691 for Single Color Lighting (Single Module shown)
VDD
Csup
100nF
Rvdd
Cvdd
100nF
UV
VREG
15
UV1
22
CURR1
1
Vc
UV2
20
CURR2
17
Vc
UV3
10
CURR3
13
Vc
UV4
8
Vc
CURR4
5
UV
VDD
AS3691
D1
Ref
T1
I1
R1
23
ON1
2 24
RFB1
19
RES1 ON2
R2
16 18
RFB2
T2
I2
R3
11
RES2 ON3
14 12
RFB3
T3
I3
R4
7
RES3 ON4
4
RFB4
6
T4
I4
Overtemp
21,Pad
VSS
RES4
Ri1
VSS
Ri2
Ri3
Ri4
VSS
PWM
PW M
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Revision 1.2
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